Control and operation in wireless local area network

ABSTRACT

Systems, methods, and instrumentalities are disclosed for range extension, basic service set (BSS) color labeling, and multi-user (MU) fragmentation and control in WLANs. A range extension notification/enablement scheme, a clear channel assessment (CCA), a headroom indication, and/or power scaling may be provided for a range extension mode. BSS color may be provided for multiple-BSSs under an access point (AP). Uplink (UL) transmission may be provided with different fragmentation capabilities. A high-efficiency (HE) trigger-based UL NDP physical layer convergence protocol (PLCP) protocol data unit (PPDU) frame may be provided. A station (STA) may receive a trigger frame comprising a null data packet (NDP) indication and a trigger type. The STA may determine that the STA is an intended recipient of the trigger frame. The STA may prepare an NDP PPDU for a control frame and/or a management frame based on the trigger type.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional U.S. patentapplication No. 62/278,558, filed Jan. 14, 2016, the disclosure of whichis incorporated herein by reference in its entirety.

BACKGROUND

A Wireless Local Area Network (WLAN) may have multiple modes ofoperation, such as an Infrastructure Basic Service Set (BSS) mode and anIndependent BSS (IBSS) mode. A WLAN in Infrastructure BSS mode mayinclude an Access Point (AP) for the BSS. One or more wireless transmitreceive units (WTRUs), e.g., stations (STAs), may be associated with anAP. An AP may have access or an interface to a Distribution System (DS)or other type of wired/wireless network that carries traffic in and outof a BSS. Traffic to STAs that originates from outside a BSS may arrivethrough an AP, which may deliver the traffic to the STAs.

SUMMARY

Systems, methods, and instrumentalities related to control and operationin WLANs are disclosed. A range extension notification/enablementscheme, a clear channel assessment (CCA), a headroom indication, and/orpower scaling may be provided for a range extension mode. BSS color maybe provided for multiple-BSSs under an AP. Uplink (UL) transmission maybe provided with different fragmentation capabilities. A high-efficiency(HE) trigger-based UL null data packet (NDP) physical layer convergenceprotocol (PLCP) protocol data unit (PPDU) frame may be provided.

An AP may send a frame associated with range extension discovery to aplurality of WLAN stations. The frame may be sent via orthogonalfrequency division multiple access (OFDMA) and may include informationon how the WLAN stations should respond to the frame (e.g., the framemay include an instruction for each of the plurality of WLAN stations toindicate its transmit power in a response, the frame may specify whatresources each of the plurality of WLAN stations should use for sendinga response, and/or the like). The AP may receive a response from atleast one of the plurality of WLAN stations. The response may include anindication of a transmit power of the at least one of the plurality ofWLAN stations. The response may be sent by the at least one of theplurality of WLAN stations via one of the following: OFDMA on ascheduled resource unit, OFDMA on a resource unit obtained throughfrequency domain random access, or uplink multi-user multiple-inputmultiple-output (UL-MU-MIMO). The AP may determine whether the at leastone of the plurality of WLAN stations should transmit using a rangeextension mode based on the transmit power indicated in the response.Based on a determination that the at least one of the plurality of WLANstations should transmit using the range extension mode, the AP may sendan indication to the at least one of the plurality of WLAN stations toswitch to the range extension mode.

The frame associated with range extension discovery may include a legacyshort training field (L-STF), a legacy long training field (L-LTF), afirst high efficiency SIG-A (HE-SIG-A) field, and a second HE-SIG-Afield. The L-STF and the L-LTF may be boosted by 3 dB, and the first andsecond HE-SIG-A fields may be repeated at least once in the frame. Theframe associated with range extension discovery may include one or moreof the following: an indication of a transmit power of the AP, a groupidentifier associated with one or more of the plurality of WLANstations, and an indication of a transmit power with which the pluralityof WLAN stations are expected to send their respective responses. Theindication of the transmit power of the at least one of the plurality ofWLAN stations may be included in a preamble of the response receivedfrom the at least one of the plurality of WLAN stations. The responsefrom the at least one of the plurality of WLAN stations may include anindication that the at least one of the plurality of WLAN stationsdesires to use the range extension mode. Such an indication may beincluded in an n-tone SIG field that may be part of the response fromthe at least one of the plurality of WLAN stations. The response fromthe at least one of the plurality of WLAN stations may include aMU-OFDMA control frame that in turn may include an L-STF, an L-LTF, afirst HE-SIG-A field, and a HE-SIG-A field. The L-STF and the L-LTF inthe response may be boosted by 3 dB, and the first and second HE-SIG-Afields may be repeated at least once in the MU-OFDMA control frame.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram of an example communications system in which one ormore disclosed features may be implemented.

FIG. 1B depicts an exemplary wireless transmit/receive unit, WTRU.

FIG. 1C illustrates exemplary wireless local area network (WLAN)devices.

FIG. 2 depicts an example preamble for a range extension (RE) mode and anormal mode.

FIG. 3 depicts an example RE mode with modulation.

FIG. 4 depicts an example beacon frame for multiple basic service setidentifications (BSSIDs).

FIG. 5 depicts an example fragmentation of multi-user (MU) frames.

FIGS. 6A and 6B depict an example of transmission reception using aphysical layer convergence protocol (PLCP).

FIGS. 7A and 7B depict an example of transmission reception using thePLCP and a HT-fixed format.

FIG. 8 depicts an example of enabling RE using non-beacon frames.

FIG. 9 depicts an example frame exchange for MU RE discovery.

FIG. 10 depicts an example MU orthogonal frequency-division multipleaccess (OFDMA) null data packet (NDP) for a RE response.

FIG. 11 depicts an example uplink MU OFDMA NDP for RE response using theRE format.

FIG. 12 depicts example preamble formats for HE single user (SU) PPDUand HE Extended Range SU PPDU.

FIG. 13 depicts an example power adjustment due to headroom limitations.

FIG. 14 depicts an example multiple-BSSID element format.

FIG. 15 depicts an example transmission of a trigger-based uplink NDPPPDU.

FIG. 16 depicts an example uplink MU-OFDMA NDP frame.

DETAILED DESCRIPTION

A detailed description of illustrative embodiments will now be describedwith reference to the various Figures. Although this descriptionprovides a detailed example of possible implementations, it should benoted that the details are intended to be exemplary and in no way limitthe scope of the application.

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed features may be implemented. For example, awireless network (e.g., a wireless network comprising one or morecomponents of the communications system 100) may be configured such thatbearers that extend beyond the wireless network may be assigned QoScharacteristics.

The communications system 100 may be a multiple access system thatprovides content, such as voice, data, video, messaging, broadcast,etc., to multiple wireless users. The communications system 100 mayenable multiple wireless users to access such content through thesharing of system resources, including wireless bandwidth. For example,the communications systems 100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include at leastone wireless transmit/receive unit (WTRU), such as a plurality of WTRUs,for instance WTRUs 102 a, 102 b, 102 c, and 102 d, a radio accessnetwork (RAN) 104, a core network 106, a public switched telephonenetwork (PSTN) 108, the Internet 110, and other networks 112, though itshould be appreciated that the disclosed embodiments contemplate anynumber of WTRUs, base stations, networks, and/or network elements. Eachof the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114 a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a HomeNode B, a Home eNode B, a site controller, an access point (AP), awireless router, and the like. While the base stations 114 a, 114 b areeach depicted as a single element, it should be appreciated that thebase stations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1x, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it should be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B depicts an exemplary wireless transmit/receive unit, WTRU 102.WTRU 102 may be used in one or more of the communications systemsdescribed herein. As shown in FIG. 1B, the WTRU 102 may include aprocessor 118, a transceiver 120, a transmit/receive element 122, aspeaker/microphone 124, a keypad 126, a display/touchpad 128,non-removable memory 130, removable memory 132, a power source 134, aglobal positioning system (GPS) chipset 136, and other peripherals 138.It should be appreciated that the WTRU 102 may include anysub-combination of the foregoing elements while remaining consistentwith an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it should be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It should be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It should be appreciated that the WTRU 102may acquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C illustrates exemplary wireless local area network (WLAN)devices. One or more of the devices may be used to implement one or moreof the features described herein. The WLAN may include, but is notlimited to, access point (AP) 202, station (STA) 210, and STA 212. STA210 and 212 may be associated with AP 202. The WLAN may be configured toimplement one or more protocols of the IEEE 802.11 communicationstandard, which may include a channel access scheme, such as DSSS, OFDM,OFDMA, etc. A WLAN may operate in a mode, e.g., an infrastructure mode,an ad-hoc mode, etc.

A WLAN operating in an infrastructure mode may comprise one or more APscommunicating with one or more associated STAs. An AP and STA(s)associated with the AP may comprise a basic service set (BSS). Forexample, AP 202, STA 210, and STA 212 may comprise BSS 222. An extendedservice set (ESS) may comprise one or more APs (with one or more BSSs)and STA(s) associated with the APs. An AP may have access to, and/orinterface to, distribution system (DS) 216, which may be wired and/orwireless and may carry traffic to and/or from the AP. Traffic to a STAin the WLAN originating from outside the WLAN may be received at an APin the WLAN, which may send the traffic to the STA in the WLAN. Trafficoriginating from a STA in the WLAN to a destination outside the WLAN,e.g., to server 218, may be sent to an AP in the WLAN, which may sendthe traffic to the destination, e.g., via DS 216 to network 214 to besent to server 218. Traffic between STAs within the WLAN may be sentthrough one or more APs. For example, a source STA (e.g., STA 110) mayhave traffic intended for a destination STA (e.g., STA 212). STA 210 maysend the traffic to AP 202, and, AP 202 may send the traffic to STA 212.

A WLAN may operate in an ad-hoc mode. The ad-hoc mode WLAN may bereferred to as independent basic service set (IBBS). In an ad-hoc modeWLAN, the STAs may communicate directly with each other (e.g., STA 210may communicate with STA 212 without such communication being routedthrough an AP).

IEEE 802.11 devices (e.g., IEEE 802.11 APs in a BSS) may use beaconframes to announce the existence of a WLAN network. An AP, such as AP202, may transmit a beacon on a channel, e.g., a fixed channel, such asa primary channel. A STA may use a channel, such as the primary channel,to establish a connection with an AP.

STA(s) and/or AP(s) may use a Carrier Sense Multiple Access withCollision Avoidance (CSMA/CA) channel access mechanism. In CSMA/CA a STAand/or an AP may sense the primary channel. For example, if a STA hasdata to send, the STA may sense the primary channel. If the primarychannel is detected to be busy, the STA may back off. For example, aWLAN or portion thereof may be configured so that one STA may transmitat a given time, e.g., in a given BSS. Channel access may include RTSand/or CTS signaling. For example, an exchange of a request to send(RTS) frame may be transmitted by a sending device and a clear to send(CTS) frame that may be sent by a receiving device. For example, if anAP has data to send to a STA, the AP may send an RTS frame to the STA.If the STA is ready to receive data, the STA may respond with a CTSframe. The CTS frame may include a time value that may alert other STAsto hold off from accessing the medium while the AP initiating the RTSmay transmit its data. On receiving the CTS frame from the STA, the APmay send the data to the STA.

A device may reserve spectrum via a network allocation vector (NAV)field. For example, in an IEEE 802.11 frame, the NAV field may be usedto reserve a channel for a time period. A STA that wants to transmitdata may set the NAV to the time for which it may expect to use thechannel. When a STA sets the NAV, the NAV may be set for an associatedWLAN or subset thereof (e.g., a BSS). Other STAs may count down the NAVto zero. When the counter reaches a value of zero, the NAV functionalitymay indicate to the other STA that the channel is now available.

The devices in a WLAN, such as an AP or STA, may include one or more ofthe following: a processor, a memory, a radio receiver and/ortransmitter (e.g., which may be combined in a transceiver), one or moreantennas (e.g., antennas 206 in FIG. 1C), etc. A processor function maycomprise one or more processors. For example, the processor may compriseone or more of: a general purpose processor, a special purpose processor(e.g., a baseband processor, a MAC processor, etc.), a digital signalprocessor (DSP), Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Array (FPGAs) circuits, any other type of integratedcircuit (IC), a state machine, and the like. The one or more processorsmay be integrated or not integrated with each other. The processor(e.g., the one or more processors or a subset thereof) may be integratedwith one or more other functions (e.g., other functions such as memory).The processor may perform signal coding, data processing, power control,input/output processing, modulation, demodulation, and/or any otherfunctionality that may enable the device to operate in a wirelessenvironment, such as the WLAN of FIG. 1C. The processor may beconfigured to execute processor executable code (e.g., instructions)including, for example, software and/or firmware instructions. Forexample, the processer may be configured to execute computer readableinstructions included on one or more of the processor (e.g., a chipsetthat includes memory and a processor) or memory. Execution of theinstructions may cause the device to perform one or more of thefunctions described herein.

A device may include one or more antennas. The device may employmultiple input multiple output (MIMO) techniques. The one or moreantennas may receive a radio signal. The processor may receive the radiosignal, e.g., via the one or more antennas. The one or more antennas maytransmit a radio signal (e.g., based on a signal sent from theprocessor).

The device may have a memory that may include one or more devices forstoring programming and/or data, such as processor executable code orinstructions (e.g., software, firmware, etc.), electronic data,databases, or other digital information. The memory may include one ormore memory units. One or more memory units may be integrated with oneor more other functions (e.g., other functions included in the device,such as the processor). The memory may include a read-only memory (ROM)(e.g., erasable programmable read only memory (EPROM), electricallyerasable programmable read only memory (EEPROM), etc.), random accessmemory (RAM), magnetic disk storage media, optical storage media, flashmemory devices, and/or other non-transitory computer-readable media forstoring information. The memory may be coupled to the processer. Theprocesser may communicate with one or more entities of memory, e.g., viaa system bus, directly, etc.

A WLAN may have multiple modes of operation, such as an InfrastructureBasic Service Set (BSS) mode and an Independent BSS (IBSS) mode. A WLANin Infrastructure BSS mode may have an AP for the BSS. One or more STAs(e.g., WTRUs) may be associated with the AP. The AP may have access oran interface to a Distribution System (DS) or other types ofwired/wireless networks that carry traffic in and out of the BSS.Traffic to the STAs that originates from outside the BSS may arrivethrough the AP, which may deliver the traffic to the STAs. Trafficoriginating from the STAs to destinations outside the BSS may be sent tothe AP, which may deliver the traffic to respective destinations.Traffic between the STAs within the BSS may be sent through the AP,e.g., from a source STA to the AP and from the AP to the destinationSTA. Traffic between the STAs within the BSS may be peer-to-peertraffic. Peer-to-peer traffic may be sent directly between the sourceand destination STAs, for example, with a direct link setup (DLS) usingan 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN in IndependentBSS (IBSS) mode may not have an AP, and, STAs may communicate directlywith each other. An IBSS mode of communication may be referred to as an“ad-hoc” mode of communication.

An AP may transmit a beacon on a fixed channel (e.g., a primarychannel), for example, in an 802.11ac infrastructure mode of operation.A channel may be, for example, 20 MHz wide. A channel may be anoperating channel of a BSS. A channel may be used by STAs, for example,to establish a connection with an AP. An example channel accessmechanism in an 802.11 system may be Carrier Sense Multiple Access withCollision Avoidance (CSMA/CA). An STA, including an AP, may sense aprimary channel, for example, in a CSMA/CA mode of operation. An STA mayback off from a channel, for example, when the channel is detected to bebusy to enable one STA to transmit at a time in a given BSS.

High Throughput (HT) STAs may use, for example, a 40 MHz wide channelfor communication (e.g., in 802.11n). A primary 20 MHz channel may becombined with an adjacent 20 MHz channel to form a 40 MHz widecontiguous channel.

Very High Throughput (VHT) STAs may support, for example, 20 MHz, 40MHz, 80 MHz and 160 MHz wide channels (e.g., in 802.11ac). 40 MHz and 80MHz channels may be formed, for example, by combining contiguous 20 MHzchannels. A 160 MHz channel may be formed, for example, by combiningeight contiguous 20 MHz channels or by combining two non-contiguous 80MHz channels, which may be referred to as an 80+80 configuration. An80+80 configuration may be passed through a segment parser that dividesdata into two streams, for example, after channel encoding. Inverse FastFourier Transform (IFFT) and time domain processing may be performed,for example, on each stream separately. Streams may be mapped onto twochannels. Data may be transmitted on the two channels. A receiver mayreverse a transmitter mechanism. A receiver may recombine datatransmitted on multiple channels. Recombined data may be sent to MediaAccess Control (MAC).

Sub-GHz (e.g. MHz) modes of operation may be supported, for example, by802.11af and 802.11ah. Channel operating bandwidths and carriers may bereduced, for example, relative to the bandwidths and carriers used in802.11n and 802.11ac. 802.11af may support, for example, 5 MHz, 10 MHzand 20 MHz bandwidths in a TV White Space (TVWS) spectrum. 802.11ah maysupport, for example, 1 MHz, 2 MHz, 4 MHz, 8 MHz and 16 MHz bandwidthsin non-TVWS spectrum. An example of a use case for 802.11ah may besupport for Meter Type Control (MTC) devices in a macro coverage area.MTC devices may have limited capabilities (e.g. limited bandwidths) andmay be designed to have a long battery life.

WLAN systems (e.g. 802.11n, 802.11ac, 802.11af and 802.11ah systems) maysupport multiple channels and channel widths, such as a channeldesignated as a primary channel. A primary channel may, for example,have a bandwidth equal to the largest common operating bandwidthsupported by STAs in a BSS. Bandwidth of a primary channel may belimited by an STA that supports the smallest bandwidth operating mode.In an example of 802.11ah, a primary channel may be 1 MHz wide, forexample, when one or more STAs (e.g., MTC type devices) support a 1 MHzmode while an AP and other STAs support a 2 MHz, 4 MHz, 8 MHz, 16 MHz orother channel bandwidth operating modes. Carrier sensing and NAVsettings may depend on the status of a primary channel. As an example,all available frequency bands may be considered busy despite some of thebands being idle and/or available, when a primary channel has a busystatus (e.g., because an STA that supports only a 1 MHz operating modeis transmitting to an AP on the primary channel).

Available frequency bands may vary between different regions. Forexample, available frequency bands used by 802.11ah may be 902 MHz to928 MHz in the United States, 917.5 MHz to 923.5 MHz in Korea, and 916.5MHz to 927.5 MHz in Japan. Total bandwidth available may vary betweendifferent regions. As an example, the total bandwidth available for802.11ah may be 6 MHz to 26 MHz depending on the country code.

IEEE 802.11™ High Efficiency WLAN (HEW) may enhance the quality ofservice (QoS) experienced by wireless users in many usage scenarios,such as high-density deployments of APs and STAs in 2.4 GHz and 5 GHzbands. HEW Radio Resource Management (RRM) technologies may support avariety of applications or usage scenarios, such as data delivery forstadium events, high user density scenarios such as train stations orenterprise/retail environments, video delivery and wireless services formedical applications. HEW may be implemented, for example, in IEEE802.11ax.

Short packets, which may be generated by network applications, may beapplicable in a variety of applications, such as virtual office, TPCacknowledge (ACK), Video streaming ACK, device/controller (e.g. mice,keyboards, game controls), access (e.g. probe request/response), networkselection (e.g. probe requests, Access Network Query Protocol (ANQP))and network management (e.g. control frames).

MU features, such as uplink (UL) and downlink (DL) OrthogonalFrequency-Division Multiple Access (OFDMA) and UL and DL MU-MIMO, may beimplemented. OFDMA may exploit channel selectivity, for example, toimprove or maximize frequency selective multiplexing gain in densenetwork conditions. A mechanism may be designed and defined forfeedback, for example, to enable fast link adaptation, frequencyselective scheduling and resource unit based feedback.

A range extension mode may be implemented. A conventional rangeextension mode may be a single user (SU) range extension mode. Such arange extension mode may be used for example, for one or moretransmissions where a receiver may experience a large path-loss and/or achannel delay spread (e.g., such as in outdoor hotspots).

FIG. 2 depicts example preambles for a range extension mode and a normalmode. The preambles in both modes may include a High-Efficiency SIG-A(HE-SIG-A) field. In the range extension mode, the preamble may becharacterized by one or more of the following. The HE-SIG-A field may betime-repeated (e.g., shown as HE-SIG-A1′ and HE-SIG-A2′). A bitinterleaver may be bypassed in one or more repeated HE-SIG-A symbols.Enablement of the range extension mode may be indicated (e.g., in thepreamble or by the format of the preamble). For example, the rangeextension mode may be indicated before the HE-SIG-A field. The rangeextension mode may be indicated by setting the length of a legacy signal(L-SIG) field to a specific value (e.g., L-SIG length mod 2=2), and/orby transmitting the HE-SIG-A1′ field using QBPSK symbols (e.g., as shownin FIG. 3). A non-high throughput (HT) legacy short training field(L-STF) and/or a non-HT legacy long training field (L-LTF) field may bepower-boosted (e.g., by 3 dB).

FIG. 3 depicts an example range extension mode with modulation in whicha single user range extension mode may be indicated by transmitting aHE-SIG-A2′ field using QBPSK.

An AP may determine to use the range extension mode. The AP may use anetwork deployment and/or a channel measurement to determine whether touse the range extension mode. An AP may support two or more BSSs. Forexample, multiple BSS Identifier (BSSID) capability may enable supportof two or more BSSs (e.g., virtual BSSs) by an AP. Information formultiple BSSIDs may be advertised. The information for multiple BSSIDsmay be advertised using a beacon frame and/or a probe response frame(e.g., a single beacon frame and/or a single probe response frame).

FIG. 4 depicts an example beacon frame for multiple BSSIDs. A field(e.g., MaxBSSID Indicator) may be designated in a beacon frame toindicate whether multiple BSSIDs (e.g., multiple virtual BSSIDs within aphysical BSS) are configured and/or the number of BSSIDs configured. Twoor more virtual BSSs may be attached to the same or different radios inan AP. The AP may trigger one or more STAs associated with a virtual BSSfor an UL multi-user (MU) transmission and/or random access. The AP maytrigger one or more STAs associated with two or more virtual BSSs for ULMU transmission and/or random access.

BSS color and/or spatial reuse may be provided in a dense network. A STAmay detect a frame and determine whether the detected frame is aninter/overlapping-BSS or an intra-BSS frame. The STA may use a BSS colorand/or a MAC address in the MAC header to determine whether the detectedframe is an inter/overlapping-BSS or an intra-BSS frame. One or morepreamble detect (PD) energy levels may be set to different values (e.g.,to improve spatial reuse). The one or more PD energy levels may be setbased on whether the detected frame is an intra-BSS (BSS PD) or anoverlapping-BSS frame (OBSS PD). A high efficiency (HE) STA may identifyand/or remember one or more NAVs set by an intra-BSS frame and/or anOBSS frame. A contention free (CF)-end frame (e.g., from an intra-BSS)may not reset a NAV set by an OBSS frame. The HE STA may determine whichBSS is the origin of a frame. For example, the HE STA may use a BSScolor to determine which BSS is the origin of the frame.

A STA (e.g., an HE STA) may identify an intra-BSS transmission. The STAmay use a BSS color to identify the intra-BSS transmission. The STA mayenter a power save mode (e.g., if a transmission is not meant for theSTA). The power save mode may comprise a doze state. An HE non-AP STAmay enter the doze state. The HE non-AP STA may remain in the doze stateuntil the end of an HE DL MU PPDU. The HE non-AP STA may enter and/orremain in the doze state until the end of the HE DL MU PPDU if thePPDU's BSS Color field is equal to the BSS color of its BSS and/or if avalue derived from a STA's identifier in the HE-SIG-B field does notmatch the HE non-AP STA's identifier or a broadcast/multicastidentifier. The HE non-AP STA may enter the doze state and/or remain inthe doze state until the end of an HE UL MU PPDU if the PPDU's BSS Colorfield is equal to the BSS color of the HE non-AP STA BSS. The HE STA mayenter the doze state and/or remain in the doze state until the end of anHE SU PPDU if the PPDU's BSS color field is equal to the BSS color ofthe HE STA BSS and/or if the UL/DL Flag field indicates that the frameis an UL frame.

Fragmentation of multi-user frames may be provided. Fragmentation mayenable efficient use of resources in multi-user transmissions.Fragmentation may enable one or more STAs to transmit in the allocatedresources with a granularity less than a complete MSDU.

FIG. 5 depicts an example fragmentation of multi-user frames. One ormore (e.g., 4) levels of fragmentation capability may be used, e.g.,negotiated between the AP and one or more STAs. The one or more levelsof fragmentation may comprise Level 0, Level 1, Level 2, and/or Level 3.Level 0 may comprise no support for fragmentation. Level 1 may comprisesupport for a fragment in a Very High Throughput (VHT) MAC Protocol DataUnit (MPDU) (e.g., a single MPDU). Level 2 may comprise support for onefragment per MSDU in an Aggregated MPDU (A-MPDU). Level 3 may supportmultiple fragments of an MSDU per A-MPDU.

As described herein, an AP may determine to use the range extension modebased on network configuration and/or a measurement. When L-STF and/orL-LTF boosting is performed in the range extension mode, an energy-basedclear channel assessment (CCA) may be incorrect. For example, the energymeasured in the L-STF and/or in the L-LTF may not equal the energy usedin a transmission.

FIGS. 6A and 6B depict an example of transmission reception using aphysical layer convergence protocol (PLCP) as provided in the OFDM PHYspecification. FIGS. 7A and 7B depict an example of transmissionreception using the PLCP and a HT-mixed format. A PMD_RSSI indicationmay be used to derive a PHY_CCA indication (e.g., for the OFDM PHYspecification and/or for the HT mixed format). The PMD_RSSI indicationmay be measured from a STF (e.g., the Legacy STF), which may not equalthe energy used in transmission. To enhance the accuracy of energyestimation, the actual receive energy in the channel may be estimated.The actual receive energy in the channel may be determined so as not toover-estimate the energy in the channel during CCA.

In certain situations (e.g., when a STA may be close to and/or exceedits maximum transmit power, and may not have enough headroom to boostthe LTF by 3 dB), range extension may be enabled. Range extension mayfocus on not only single-user transmissions, but also multi-usertransmissions. Range extension may be enabled for one or more STAs orfor an entire BSS.

A physical AP may support two or more (e.g., multiple) BSSs. The BSSsmay comprise a virtual BSS. One or more BSS colors may be provided forthe BSSs. Each of the BSSs may be allocated a BSS color. Setting aspatial reuse (e.g., a NAV setting and/or one or more CF-END resets)and/or a power save behavior based on the BSS color may be unreliable(e.g., if each BSS of the multiple BSSs is allocated a different BSScolor). A BSS color may be determined for the multiple BSSs and/or STAs(e.g., to enable proper spatial reuse and/or power savings).

An AP may transmit to two or more STAs with different negotiatedfragmentation levels. The two or more STAs may comprise different STAfragmentation capabilities. Each of the two or more STAs may decodeallocated resources independently based on the fragmentationcapabilities. The AP may receive data from the two or more STAs, and maynegotiate one or more fragmentation levels for the two or more STAs.

One or more control frames may be exchanged between an AP and itsassociated STAs (e.g., in a multi-user (MU) transmission). A MU UL PPDUmay comprise UL control information (e.g., in one or more controlframes). The MU UL PPDU may comprise multiple MAC frames from multipleusers. A MAC control frame (e.g., a full MAC control frame) may comprisea MAC header and a MAC body. Using a full MAC control frame to sendlimited control information may not be efficient.

A range extension mode may be enabled for an AP and/or a STA. The rangeextension mode may be STA-specific. For example, the range extensionmode may apply to a particular STA, or a group of STAs (e.g., two ormore STAs, e.g., belonging to a same group). The range extension modemay be BSS-wide. For example, the range extension mode may apply tospecific STA(s) (e.g., all STAs) in a BSS. In BSS-wide range extension,an AP may demand that the STAs (e.g., all STAs) in the BSS transmitusing the range extension mode. In STA-specific range extension, the APmay communicate with (e.g., transmit to and/or receive from) from firstSTA or a first group of one or more STAs using the range extension mode,and communicate with (e.g., transmit to and/or receive from) a secondSTA or a second group of one or more STAs using the normal mode.

An AP may signal a range extension mode in a beacon frame (e.g., toindicate and/or enable BSS-wide range extension). The signaling may bereceived by one or more STAs (e.g., all STAs in a BSS). The signalingmay comprise a range extension mandatory bit, which may indicate to thereceiving STAs to transmit using the range extension mode. The signalingmay comprise a group id field to indicate to the STAs associated withthe group id to enter the range extension mode. The signaling mayinclude individual STA identifiers to indicate to the STAs that areassociated with the identifiers to enter the range extension mode. TheAP may determine and use a specific beacon frame format for signalingthe range extension mode. The detection of the range extension frameformat may trigger the receiving STAs to enable and/or use the rangeextension mode (e.g., the STAs may transmit using the range extensionmode).

FIG. 8 depicts an example of indicating, enabling, and/or using rangeextension via non-beacon frames. The technique may be used, for example,to enable STA-specific range extension or BSS-wide range extension. ASTA may send a request frame (e.g., xRequest in FIG. 8) to an associatedAP. The request frame may be a MAC frame. The request frame may comprisea probe request, an association request, and/or a range extensionrequest. The STA may indicate its transmit power (e.g., Tx power in FIG.8) in the request frame (e.g., so that the AP can compare the transmitpower with a measured power of the transmission channel to determine apath loss). The transmit power used by the STA may be indicated in apreamble (e.g., as part of a HE-SIG-A field). The transmit power used bythe STA may be indicated as part of a HE-SIG-B field. The AP may measurethe received power of the request frame, compare the indicated transmitpower with the received power, and determine whether range extensionshould be enabled for the STA (e.g., based on the difference between thetransmit power and the received power, which may provide an indicationof path loss).

The AP may send a response frame (e.g., xResponse in FIG. 8) to the STA.The response frame may comprise a probe response, an associationresponse, and/or a range extension response frame. The response framemay comprise signaling (e.g., an instruction) for the STA to enable therange extension mode. The signaling may comprise a range extensionenable bit. The signaling may instruct the STA to transmit using therange extension mode. The AP may send the response frame using the rangeextension mode. The use of the range extension mode may implicitlyindicate to the STA that transmissions by the STA should use the rangeextension mode.

The AP may send an unsolicited frame to the STA (e.g., without firstreceiving a range extension request). The frame may indicate that theSTA should switch to transmitting in the range extension mode. Theindication may be explicit. For example, the indication may beimplemented via a range extension enable bit comprised in theunsolicited frame. The indication may be implicit. For example, theindication may be provided by sending the unsolicited frame using therange extension mode.

The example techniques described herein may also be used to enableBSS-wide range extension or to enable range extension for specificSTA(s) (e.g., a group of one or more STAs). For example, the STAs (e.g.,all STAs) in a BSS may each send a range extension request to anassociated AP, and receive signaling from the AP allowing or instructingthe STAs to switch to the range extension mode. The signaling may beexplicit, e.g., by including a range extension enable bit in a responseframe, or implicit, e.g., by sending a response frame using the rangeextension mode. The AP may send an unsolicited (e.g., without receivinga request frame) instruction (e.g., via a frame) to the STAs (e.g., allSTAs) in a BSS to switch those STAs to the range extension mode. Anunsolicited instruction may include a range extension enable bit, or besent using the range extension mode to implicitly direct the receivingSTAs to transmit using the range extension mode. The unsolicitedinstruction may be sent in a beacon frame. The instruction may include agroup id field (e.g., to indicate to the STAs associated with the groupid that they should enter the range extension mode) and/or individualSTA identifiers (e.g., to indicate to the STAs associated withindividual identifiers that they should enter the range extension mode).In such cases, the beacon frame may be received by multiple STAs, butthe STAs switching to the range extension mode may be limited to thoseSTAs with a matching group id.

An AP may determine which STAs should switch to the range extensionmode. The AP may conduct range extension discovery. In the rangeextension discovery, the AP may determine which STAs need rangeextension. One or more STAs may determine to drop range extension. Theone or more STAs may indicate to the AP that the one or more STAs maydrop range extension.

FIG. 9 depicts an example frame exchange for MU range extensiondiscovery. The AP may send a range extension (RE) discovery frame (e.g.,such as a multi-user discovery request shown in FIG. 9). The REdiscovery frame may initiate the range extension discovery mode. The REdiscovery frame may be sent to a specific STA (e.g., the RE discoveryframe may request a response frame back from the STA). The RE discoveryframe may be sent to a plurality of STAs. The RE discovery frame maycomprise a scheduled OFDMA trigger frame (e.g., in which the AP mayschedule one or more specific STAs and/or request some or all of theSTAs to send an OFMDA/UL-MU-MIMO response back). The RE trigger framemay comprise a normal trigger frame with a flag (e.g., a one-bit field).The flag may indicate to one or more STAs to send a transmit power tothe AP. The RE trigger frame may comprise information regarding whatresources a STA should use for sending a response. The RE trigger framemay comprise an instruction/indication for multiple STAs that receivethe trigger frame to send an OFDMA/UL-MU-MIMO response back. The REtrigger frame may comprise the transmit power of the AP. The one or moreSTAs may estimate the path loss based on the transmit power of the AP.The one or more STAs may determine (e.g., respectively) whether theyshould use range extension based on the estimated path loss. The REtrigger frame may be sent using the range extension mode (e.g., toensure that the STAs are able to receive the RE trigger frame). The REtrigger frame may comprise a 3dB boost to one or more of the preamblefields (e.g., the L-STF and/or L-LTF). The RE trigger frame may repeatthe HE-SIG-A1 and/or HE-SIG-A2.

Each of the one or more STAs (e.g., each scheduled STA) may sendinformation on whether it needs range extension or not. For example,each of the one or more STAs may send a response frame (e.g., such as aMU NDP response frame) to the AP. The response frame may be based on theAP polling a STA (e.g., the response may be sent by a STA in response tothe STA receiving the range extension discovery frame from the AP). Theresponse frame may be sent across the entire transmission bandwidth. Theresponse frame may be sent across part of the entire transmissionbandwidth. The response frame may be based on the AP initiating amulti-user transmission (e.g., the response may be sent via OFDMA and/orUL-MU-MIMO). The response frame may be sent on a scheduled resource unit(RU) using UL OFDMA. The response frame may be sent on an RU obtainedusing frequency domain random access (e.g., using UL-OFDMA). Theresponse frame may be sent (e.g., simultaneously) from two or more STAs(e.g., using UL-MU-MIMO).

The response frame may indicate a transmit power of the STA. The AP maydetermine if range extension is needed based on the transmit power ofthe STA. The response frame may comprise a flag (e.g., a one-bit field)set by the STA that indicates if range extension is needed. The transmitpower and/or the flag may be sent in the response frame preamble (e.g.,to reduce the feedback overhead). For example, the transmit power and/orthe flag may be sent in a HE-SIG-A field and/or a HE-SIG-B field.Alternatively or additionally, the transmit power and/or the flag may besent in a MAC frame.

The STA may set a particular power level for sending the response frame(e.g., to ensure that the AP successfully receives the frame). The STAmay determine the power level via one or more of the following. The APdiscovery request frame may indicate a transmit power of the AP (e.g.,so that the STA may determine its own transmit power based on thetransmit power of the AP). The AP discovery request frame may indicate atransmit power that should be used by a STA. The AP discovery requestframe may indicate a desired receive power at the AP (e.g., to ensuresuccessful reception of the response frame from the STA). The responseframe may be transmitted using UL-OFDMA (e.g., the transmission may usea maximum transmit power in a bandwidth RU (e.g., a small bandwidth RU),which may increase transmit power spectral density and/or may ensureproper reception of the response frame).

The AP may acknowledge the receipt of a response frame. Theacknowledgment may be sent via a MU ACK, as shown in FIG. 9.

A UL-OFDMA response frame may comprise an UL-OFDMA control frame (e.g.,such as an OFDMA null data packet). The UL-OFDMA control frame mayinclude a pre-defined control and/or signal field within a specific RU.The pre-defined control and/or signal field may be referred to herein asan HE-SIG-C field.

FIG. 10 depicts an example uplink MU OFDMA null data packet for a rangeextension response. The UL-OFDMA control frame may fit within a singlen-tone RU (e.g., a n-tone RU may be a RU that includes n subcarriers,e.g., n may have a value of 26, 52, 104, and/or the like). The UL-OFDMAcontrol frame may comprise an HE-STF field. The HE-STF field maycomprise an n-tone STF. The HE-STF field may depend on the size and/orposition of the RU. The HE-STF field may span the entire transmissionbandwidth. The UL-OFDMA control frame may comprise an HE-LTF field. TheHE-LTF field may comprise an n-tone LTF. The HE-LTF field may depend onthe size and/or position of the RU. The HE-LTF field may span the entiretransmission bandwidth. The UL-OFDMA control frame may comprise anHE-SIG-C field. The HE-SIG-C field may comprise an n-tone SIG field. TheHE-SIG-C field may comprise (e.g., be filled with or fixed with)different bits representing information to be sent to the AP. Forexample, a bit of the HE-SIG-C field may be set to indicate a rangeextension mode on/off. Bit representation of the HE-SIG-C field (e.g.,composition of the HE-SIG-C field) may depend on a specific triggerrequest from the AP (e.g., depend on the information sought in thetrigger request). For example, a range extension indication flag and/orother information may be sent back to the AP.

FIG. 11 depicts an example UL MU OFDMA null data packet for a rangeextension response using an example range extension format. The exampleformat may be employed in a multi-user request and/or response that isset to use the range extension mode. In such scenarios, the L-STF fieldand/or the L-LTF field may be boosted (e.g., by 3 dB). The SIG-A field(e.g., HE-SIG-A1 and HE-SIG-A2 fields) may be repeated, for example toensure that the link between AP and STAs may be closed (e.g., to ensurethat the power received at the STAs based on a signal transmission forthe AP is able to support the transmission of data).

A clear channel assessment (CCA) may be provided in the range extensionmode. As described herein, a node (e.g., such as an AP or a STA) maymeasure the received signal strength information (RSSI) based on theL-STF field in a preamble. The node may set a value for aPMD.RSSI_indication field (e.g., based on the measured RSSI). ThePMD.RSSI_indication value may be used by the MAC to set a value for aPHY_CCA.indication field (e.g., by comparing the PMD.RSSI_indicationvalue with the specific energy detection threshold required). If thepreamble is decoded, a preamble detection CCA threshold may be used as acomparison. If the preamble is not decoded, an energy detection CCAthreshold (e.g., which may be greater than the preamble detection CCAthreshold) may be used as a comparison. In range extension scenarios,the PMD.RSSI_indication field may over-estimate the energy in thechannel (e.g., because the L-LTF field may have been boosted by 3dB).The over-estimated channel energy indicated in the PMD.RSSI_indicationfield may reduce network throughput (e.g., in dense networks).

FIG. 12 depicts example preamble formats for HE SU PPDU and HE ExtendedRange SU PPDU. Both preambles may include a L-STF field and/or a L-LTFfield. For HE Extended Range SU PPDU, either or both of the L-STF fieldand the L-LTF field may be boosted (e.g., by 3 dB). The HE-SIG-A1 fieldand/or the HE-SIG-A2 field may be repeated in the HE Extended Range SUPPDU.

For HE-STAs, the CCA may be modified (e.g., to take into account theincreased energy measured in the range extension mode) according to oneor more of the following rules. When there is no change in the behaviorof the HE-STA, the HE-STA may use, for example, the RSSI estimated fromthe L-STF field. When a preamble is not detected, the CCA may or may notbe modified (e.g., since an energy detection threshold may be large).When a preamble is detected, the CCA may be modified. The HE-STA maymodify its behavior to take into account the energy boost of the L-STFand/or L-LTF. The HE-STA may adjust the RSSI.indication (e.g., toaccount for the boost). The HE-STA may adjust the RSSI.indication by afactor (e.g., reduce the PMD.RSSI_indication by 3 dB). The HE-STA mayreduce the PMD.RSSI indication by an implementation specific value(e.g., because the changes may not be linear).

The HE-STA may measure the RSSI of the HE-STF. The HE-STA may use themeasured RSSI value to set the PHY_CCA.indication. The HE-STA may detectthe L-STF. The HE-STA may estimate the RSSI. The HE-STA may include theestimated RSSI in the PMD.RSSI_indication. The HE-STA may detect arepeated L-SIG field. The repeated L-SIG field may indicate that thepacket is an HE packet. The HE-STA may detect an HE-SIG-A2 field as aQBPSK, which may indicate an HE extended range SU PPDU. The HE-STA maydecode a repeated HE-SIG-A field. The HE-STA may detect an HE-STF. TheHE-STA may determine a re-estimated RSSI. The HE-STA may include there-estimated RSSI in the PMD.RSSI. The HE-STA may estimate thePHY_CCA.indication using the PMD.RSSI.

A headroom indication may be provided for the range extension mode. Whena STA transmits near a maximum power, the STA may not have the extrapower to boost its L-STF and/or L-LTF (e.g., by 3 dB). The STA mayindicate a power headroom to the AP (e.g., during a measurement for REand/or during association with the AP), in addition to or in lieu ofindicating a transmit power. The power headroom indication may comprisethe maximum power the STA may transmit. The power headroom indicationmay comprise a change in power allowed by the STA.

When associating with the AP (e.g., during Range Extension discoveryand/or during a range extension request/response frame exchange), theSTA may send transmit power information and/or transmit power headroom(e.g., a transmit power headroom indication) to the AP. If the powerheadroom is less than 3 dB, the AP may decide not to place the STA inthe range extension mode.

FIG. 13 depicts an example of power adjustment due to headroomlimitations. The AP may decide to request that the STA transmit all orpart of the PPDU (e.g., excluding the L-STF/L-LTF) with a lower transmitpower (e.g., in order to allow the 3 dB of headroom necessary for rangeextension). The STA may decide (e.g., in response to a request from theAP or autonomously without a request from the AP) to scale the transmitpower of the STA (e.g., to ensure that the ratio is kept constant). Forexample, the STA may transmit at 5 Watts with a headroom of 2 Watts(e.g., the maximum transmit power of the STA may be 7 Watts). Powerboosting may require a transmit energy of 10 Watts. The STA may transmitthe entire packet at 3.5 Watts with power boosting (e.g., as opposed totransmitting with 5 Watts without power boosting). The STA may transmita portion of the packet (e.g., before HE-STF) at 3.5 Watts with powerboosting (e.g., as opposed to transmitting the portion with 5 Wattswithout power boosting), and may transmit the remainder of the packet(e.g., starting from the HE-STF) at 5 Watts.

The AP may allow the STA to boost LTF by a value lower than 3 dB. Thelower value may be one of a discrete set of values agreed on between atransmitter (e.g., which may be an AP or a STA) and a receiver (e.g.,which may be an AP or a STA). The lower value may be signaled (e.g., bya STA to an AP). Signaling may be used to indicate the range extensionboost value. The UL MU NDP may use one or more bits to indicate theboosting used in the L-STF and/or L-LTF. The RE response frame mayindicate the amount of boosting it is capable of. The AP may send an ACKto acknowledge receipt of the boost level from the STA.

The AP may ensure transmission from the STA by configuring the STA touse UL-OFDMA (e.g., the STA may be configured to use UL-OFDMA only). Insuch cases, a total transmit power may be scheduled in a smallerbandwidth (e.g., to increase the power spectral density).

Power scaling may be provided for a range extension mode. A STA maytransmit using a power that exceeds a maximum power after boosting itsL-STF and/or L-LTF by 3 dB. A STA may apply power scaling after itboosts its L-STF and/or L-LTF by 3 dB (e.g., before the STA transmits).The power scaling may maintain a relative power difference between apreamble and data (e.g., such that the same or similar PER performancemay be maintained for one or more fields including, for example,L-STF/LTF, L-SIG/RL-SIG and HE-SIG1/HE-SIG1′, HE-SIG2/HE-SIG2′). Thepower scaling may be an automatic STA power scaling (e.g., without APcontrol). Power scaling may be helpful in multiple aspects of the rangeextension mode (e.g., in case the AP makes a wrong decision to applypower boosting for L-STF/LTF or range extension).

BSS color may be provided for multiple-BSSs under an AP. In a single BSSscenario, one or more STAs in a BSS may use the BSS color and/or anassociated UL/DL bit to enter a power save mode. The one or more STAs inthe BSS may use the BSS color and/or an associated UL/DL bit todetermine when to set a NAV, when to use one or more OBSS preambledetect thresholds, and/or when to respond to one or more ContentionFree-End (CF-END) packets for frame protection.

When multiple-BSSs are under a physical AP, two or more radios may beprovided with multiple BSSIDs assigned to each of the two or moreradios. Power save and/or spatial reuse may be provided for two or moreradios that access the same medium (e.g., the same channel). A STA mayidentify one or more (e.g., all) of the BSSIDs that may access itsmedium.

Each BSS may be assigned a separate color. The AP may inform a STA ofone or more (e.g., all) BSS-colors that the STA should respond to (e.g.,similar to how the STA may respond to its own BSS color). A BSS may beassigned a specific BSS color and/or a BSS color group. For example, oneor more (e.g., all) BSSIDs that access the same channel (e.g., medium)may be assigned the same BSS color (e.g., to accommodate the limitednumber of available BSS colors). The STA may be informed of the BSScolor and/or the BSS color group.

A BSS color may be assigned to a (e.g., each) virtual BSS. A physical APBSS color may be determined based on the BSS color assigned to thevirtual BSS. For example, each virtual BSS may be assigned a BSS colorand/or a mask. A virtual AP associated with a virtual BSS may comprise aBSS color and/or a mask associated with the virtual BSS. The virtual APmay use an individual color and/or may identify one or more packets thatarrive from the physical AP.

FIG. 14 depicts an example multiple-BSSID element format. Themultiple-BSS element may be extended to signal one or more BSS colorsassociated with one or more (e.g., each) BSSs. The one or more BSScolors may be signaled to one or more STAs associated with a physical APand/or a specific BSS. The multiple-BSSID element may comprise optionalsub-elements. One such optional sub-element may be a MaxBSSID Indicatorfield that may indicate the number of virtual BSSs in a physical BSS.Another optional sub-element may be a BSS color field that may indicatea BSS color of a specific BSS. Another optional sub-element may be a BSScolor group field that may indicate a grouping of BSS color. The BSScolor group field may be used, for example, when each BSS is assigned aseparate BSS-color.

A physical AP BSS color may be provided with a CF-END frame. This may beillustrated in the following example in which a first STA (e.g., STA1)and a second STA (e.g., STA 2) may be associated with a first virtual AP(e.g., BSSID1), and a third STA (e.g., STA3) may be associated with asecond virtual AP (e.g., BSSID2). A physical AP (e.g., BSSID0) may beassigned BSS color 0 to indicate that one or more (e.g., all) virtualBSSs are associated with the physical AP on a medium. An example beaconframe may comprise one or more of the following elements: Element ID,Length, MaxBSSID Indicator (e.g., which may be assigned a value of 2),Physical AP BSSID (e.g., which may be assigned a value of BSS0),Physical AP BSS color (e.g., which may be assigned a value of 0);Virtual AP1 BSSID (which may be assigned a value of BSS1); Virtual APIBSS color (which may be assigned a value of 1); Virtual API BSS colorgroup (which may be assigned a value of 0); Virtual AP2 BSSID (e.g.,which may be assigned a value of BSS2); Virtual AP2 BSS color (e.g.,which may be assigned a value of 2); and Virtual BSS color group (e.g.,which may be assigned a value of 2).

The first STA may send a request to send (RTS) to the first virtual AP.The physical AP may send a clear to send (CTS) message to the first STA(e.g., while setting the BSS color and/or the physical AP BSSID to 0 inthe frame). The respective NAVs of the first STA, the second STA, andthe third STA may be set. The first STA may send a CF-END to thephysical AP. The second STA may receive (e.g., overhear) the CF-END. Thesecond STA may reset the NAV of the second STA (e.g., upon receipt ofthe CF-END). The physical AP may send a repeated CF-END (e.g., with theBSS color and/or the BSSID set to 0). The third STA may reset the NAV ofthe third STA (e.g., upon receipt of the repeated CF-END).

Uplink transmission may be provided with different fragmentationcapabilities. An AP may negotiate the fragmentation level for one ormore (e.g., each) STAs. The fragmentation level may be set as part of anassociation request/response frame exchange (e.g., during association ofa STA and an AP through an initial access).

The beacon frame and/or probe response frame from the AP may comprise apre-defined fragmentation level supported by the AP. The level may bedefined such as support for a higher fragmentation level may indicatesupport for a lower fragmentation level (e.g., if a higher fragmentationlevel is signaled, such signaling may be interpreted as implying supportfor lower levels as well). The fragmentation level may be a fixed value(e.g., indicating support for only that fragmentation level). Thefragmentation level may be varied within a range (e.g., multiple fixedvalues may be supported).

If the beacon and/or probe response frames indicate an allowance fornegotiating, the STA may indicate (e.g., propose) a fragmentation level(e.g., a desired fragmentation level). The fragmentation level may beindicated in an association request frame. The AP may indicate anacceptance or a rejection of the fragmentation level proposed by theSTA. For example the AP may set a flag in an association response frameindicating the acceptance or the rejection of the fragmentation levelproposed by the STA. If the AP accepts the fragmentation level proposedby the STA, the STA may authenticate and join the network. If the APrejects the fragmentation level proposed by the STA, the STA may notjoin the network.

Different STAs may have different fragmentation capabilities. An AP maymodify (e.g., dynamically adjust) the fragmentation level based on oneor more scheduled STAs. For example, when an AP is associated withmultiple scheduled STAs that use different fragmentation levels, the APmay modify the fragment levels of scheduled STAs (e.g., to a samelevel). The modified fragmentation capability level may be signaled in atrigger frame (e.g., in a trigger frame used to schedule one or moreusers). A specific fragmentation level (e.g., a fragmentation levelspecific to a user or a STA) may be signaled in a user- or STA-specificportion of the HE-SIG-B field.

A STA may transmit and/or receive data using a desired fragmentationlevel. The AP may determine a fragmentation level based on a lowestcommon fragmentation level of one or more STAs to be scheduled in anuplink transmission. The AP may signal the determined fragmentationlevel to the one or more STAs.

An HE trigger-based UL NDP PPDU frame may be provided, for example tocarry short uplink control and/or management information. The shortuplink control and/or management information may comprise a bufferstatus report. The buffer status report may indicate that the STA hastraffic to send. The short uplink control and/or management informationmay comprise a flag indicating a request to switch to a range extensionmode.

FIG. 15 depicts an example transmission of a trigger-based UL NDP PPDU.A transmission (e.g., a trigger-based UL NDP PPDU transmission) may beinitiated by a trigger frame. An AP may acquire the medium for thetransmission by contention and/or scheduling. The AP may transmit thetrigger frame. The trigger frame may comprise a MU PPDU format. Thetrigger frame may comprise a SU PPDU format. The trigger frame maytrigger a dedicated UL transmission and/or an UL random access. Thetrigger frame may initiate one or more trigger-based UL NDP PPDUtransmissions from one or more connected STAs. The trigger frame maycomprise a trigger type. The trigger type may indicate whether anexpected UL frame may be a small control frame or a management frame,for example. The trigger frame may comprise an NDP indication. The NDPindication may be included in a common information field and/or auser-specific information field of the trigger frame.

A STA may receive the trigger frame. Upon reception of the triggerframe, the STA may determine whether the STA is an intended recipient ofthe trigger frame. If the NDP indication is included in the triggerframe, the STA may prepare an NDP PPDU for a control and/or managementframe (e.g., based on the trigger type). If the NDP indication is notincluded in the trigger frame, the STA may prepare the transmission witha normal MAC frame.

In a trigger-based UL NDP PPDU, an UL transmission from one or more(e.g., all) of the STAs may not comprise a MAC frame. The ULtransmission may comprise a SIG field. The SIG field may comprise MACcontrol and/or management information. The AP may request that a firstSTA reply with an NDP frame while a second STA reply with a normal MACframe.

An HE trigger-based UL NDP PPDU frame may comprise a plurality of fieldsincluding, for example, an HE-SIG-C field described herein. The HE-SIG-Cfield may be defined based on a trigger type. For example, the HEtrigger-based UL NDP PPDU frame may support one or more of the followingUL NDP control/management frames: HE NDP CTS, HE NDP PS-POLL, HE NDP ULTraffic Report, HE NDP UL TXOP Request, and/or HE NDP UL ACK/BA.

The HE-SIG-C field may use an MCS set by the trigger frame. The MCS usedby the HE-SIG-C field may be signaled in an HE-SIG-A field. The HE-SIG-Cfield may be transmitted in a specific RU (e.g., as shown in FIG. 10),and be repeated with phase rotation in one or more of the remainingassigned RUs. The HE-SIG-C field may be transmitted over the assignedRUs. A same HE-SIG-C may be transmitted in each RU and diversity may beachieved by phase rotation. Different HE-SIG-Cs may be transmitted indifferent RUs dedicated to different users. A hybrid approach may beadopted (e.g., use a same HE-SIG-C and phase rotation in some RUs, anddifferent HE-SIG-Cs in other RUs).

FIG. 16 depicts an example uplink MU-OFDMA NDP frame. The HE-SIG-C fieldmay be transmitted to one or more RUs (e.g., across the entire band).The HE-SIG-C field may be separated by the AP in the spatial and/or codedomain. For example, the HE-SIG-C field may be sent in the 64 point FFTregion of the HE-PPDU.

Although the features are described herein, each feature or element maybe used without other features or in various combinations with orwithout other features.

Although 802.11 specific protocols are described herein, the featuresdescribed herein are not restricted to this scenario and may be appliedin other wireless systems.

Although SIFS is used to indicate various inter frame spacing in theexamples, other inter frame spacing such as RIFS, AIFS, DIFS or otheragreed time interval could be applied in the same solutions.

The processes described above may be implemented in a computer program,software, and/or firmware incorporated in a computer-readable medium forexecution by a computer and/or processor. Examples of computer-readablemedia include, but are not limited to, electronic signals (transmittedover wired and/or wireless connections) and/or computer-readable storagemedia. Examples of computer-readable storage media include, but are notlimited to, a read only memory (ROM), a random access memory (RAM), aregister, cache memory, semiconductor memory devices, magnetic mediasuch as, but not limited to, internal hard disks and removable disks,magneto-optical media, and/or optical media such as CD-ROM disks, and/ordigital versatile disks (DVDs). A processor in association with softwaremay be used to implement a radio frequency transceiver for use in aWTRU, terminal, base station, RNC, and/or any host computer.

1-20. (canceled)
 21. A station (STA) comprising: a transmitter, areceiver and a processor; the receiver configured to receive a triggerframe including at least an indication for uplink (UL) null data packet(NDP) frames from a plurality of STAs and a trigger type; in response tothe received trigger frame, and based on the trigger type, the processorconfigured to generate a first NDP frame; and the transmitter configuredto transmit the first NDP frame including at least a feedback report.22. The STA of claim 21, wherein: the processor is further configured toverify that the STA is an intended recipient of the trigger frame bychecking a field in the received trigger frame.
 23. The STA of claim 21,wherein the indication for UL NDP frames is in a common informationfield of the trigger frame.
 24. The STA of claim 21, wherein theindication for UL NDP frames is in a user-specific information field ofthe trigger frame.
 25. The STA of claim 21, wherein the first NDP framefurther includes an UL resource request.
 26. The STA of claim 25,wherein the UL resource request is an UL TXOP request.
 27. The STA ofclaim 21, wherein the first NDP frame is a small control frame or amanagement frame.
 28. The STA of claim 21, wherein the feedback reportis an UL traffic report.
 29. The STA of claim 21 configured as ahigh-efficiency (HE) STA.
 30. The STA of claim 21, wherein: theprocessor and transmitter are further configured to determinetransmission parameters based at least in part on the received triggerframe.
 31. A method performed by a station (STA), the method comprising:receiving a trigger frame including at least an indication for uplink(UL) null data packet (NDP) frames from a plurality of STAs and atrigger type; in response to the received trigger frame, and based onthe trigger type, generating a first NDP frame; and transmitting thefirst NDP frame including at least a feedback report.
 32. The method ofclaim 31, further comprising: verifying that the STA is an intendedrecipient of the trigger frame by checking a field in the receivedtrigger frame.
 33. The method of claim 31, wherein the indication for ULNDP frames is in a common information field of the trigger frame. 34.The method of claim 31, wherein the indication for UL NDP frames is in auser-specific information field of the trigger frame.
 35. The method ofclaim 31, wherein the first NDP frame further includes an UL resourcerequest.
 36. The method of claim 35, wherein the UL resource request isan UL TXOP request.
 37. The method of claim 31, wherein the first NDPframe is a small control frame or a management frame.
 38. The method ofclaim 31, wherein the feedback report is an UL traffic report.
 39. Themethod of claim 31, wherein the STA is configured as a high-efficiency(HE) STA.
 40. The method of claim 31, further comprising: determiningtransmission parameters based at least in part on the received triggerframe.